Benzomorphan derivatives as analgesic agents

ABSTRACT

AN ANALGESIC COMPOSITIONS IS PRODUCED WHICH COMPRISES AN ANALGESICALLY EFFECTIVE AMOUNT OF A BENZOMORPHAN OF THE FORMULA   3-R,11-R&#34;,6-R&#39;&#39;,8-(X-CO-A-O-)-1,2,3,4,5,6-HEXAHYDRO-2,6-   METHANO-3-BENZAZOCINE   WHEREIN   R IS METHYL, CYCLOPROPYLMETHYL OR CYCLOBUTYLMETHYL; R&#39;&#39; AND R&#34; ARE THE SAME OR DIFFERENT, AND ARE METHYL OR ETHYL; A IS STRAIGHT OR BRANCHED CHAIN ALKYLENE OR ALKYLIDENE OF 1 TO 4 CARBON ATOMS OR ALKENYLENE OF 2 TO 4 CARBON ATOMS, UNSUBSTITUTED OR SUBSTITUTED BYPHENYL OR PHENYL SUBSTITUTED BY METHYL, METHOXY, CHLORO, NITRO OR ACETYLAMINO; X IS   -OH, -O-R&#39;&#39;&#34;, OR -N(-R4)-R5   WHEREIN   R&#34;&#39;&#39; IS A STRAIGHT OR BRANCHED CHAIN ALKYL OF 1 TO 11 CARBON ATOMS OR STRAIGHT OF BRANCHED CHAIN ALKENYL OR 2 TO 11 CARBON ATOMS, AND R4 AND R5 ARE THE SAME OR DIFFERENT, AND ARE HYDROGEN, ALKYL OF 1 TO 4 CARBON ATOMS, OR R4 AND R5 TOGETHER WITH THE NITROGEN ATOM FORM A PYRROLIDINE, PIPERIDINE OR MORPHOLINE RING;   IN COMBINATION WITH A PHARMACEUTICALLY ACCEPTABLE, NONTOXIC INERT DILUENT OR CARRIER. THE COMPOSITION MAY BE ADMINISTERED ORALLY OR PARENTERALLY.

United States Patent 3,781,431 BENZOMORPHAN DERIVATIVES AS ANALGESIC AGENTS Hans-Werner Schubert and Friedrich Hofimeister, W uppertal-Elberfeld, Germany, assignors to Bayer Aktiengesellschaft, Leverkusen, Germany No Drawing. Original application May 14, 1970, Ser. N 0. 37,331. Divided and this application Sept. 27, 1972, Ser. No. 292,768 Claims priority, application Germany, May 17, 1969, P 19 25 296.1 Int. Cl. A611: 27/00 US. Cl. 424-267 22 Claims ABSTRACT OF THE DISCLOSURE An analgesic composition is produced which comprises an analgesically effective amount of a benzomorphan of the formula wherein wherein R'" is a straight or branched chain alkyl of l to 11 carbon atoms or straight or branched chain alkenyl of 2 to 11 carbon atoms, and

R and R are the same or different, and are hydrogen, alkyl of 1 to 4 carbon atoms, or R4 and R together with the nitrogen atom form a pyrrolidine, piperidine or morpholine ring;

in combination with a pharmaceutically acceptable, nontoxic inert diluent or carrier. The composition may be administered orally or parenterally.

This is a division of application Ser. No. 37,331, filed May 14, 1970.

The present invention is concerned with benzomorphanes and their production. These compounds are useful as analgesics.

It is known that the so-called strongly active or narcotic analgesics exhibit similar pharmacological effects to that of morphine independent of their chemical composition. As a result, such compounds cause similar con- 3,781,431 Patented Dec. 25, 1973 comitant effects and side-effects as morphine itself and at a high dosage level produce similar toxic phenomena as does morphine. Thus, the morphine-like effect of such compounds which produces morphine-like physiological and psychic dependents in humans and animals, commonly known as morphine addiction, is of great significance.

As a result of these efiects, analgesics like morphine and those which exhibit morphine-like efiects are only used under closely supervised circumstances in order to minimize the possibility of morphine addiction. Because of the likelihood of morphine addiction, such compounds cannot be used for long term pain relief. Thus, any new analgesic which exhibits a high activity level and at the same time either does not produce a morphine-like addiction or dependence, or produces an addiction or dependence which is less pronounced than morphine and the morphine-like analgesics represents a significant and important advance in the art.

Clinical-therapeutic experience has demonstrated that the analgesic effect of known strongly active analgesics is not always sufiicient for the treatment of conditions which produce severe pain, such as the pain associated with carcinoma. In such cases, the analgesic effectiveness will outweight the addictive side-effects so that analgesics which are stronger than morphine and morphine-like analgesics would be of considerable and important usage even though such compounds might cause addiction.

It is well known in the art that both the analgesic eflects and the side-effects or concomitant eifects of analgesics can be accurately determined in animal experiments. The analgesic effects are particularly reliably detected in the heat ray test on the tail of a rat, according to dAmour and Smith.

The concomitant effects and especially the addiction causing properties-of analgesics can be determined by testing such compound on morphine-dependent monkeys, i.e., monkeys addicted to morphine.

Compounds which are tested on morphine-dependent monkeys and which are either not capable of replacing morphine which exert a morphine antagonist effect in such monkeys are considered to be free of morphine addiction and dependence type properties.

The benzomorphanes of the present invention exhibit a high level of analgesic activity and are superior to such known strong analgesics as morphine, codeine and pethidine. The benzomorphanes of the present invention are superior to these known analgesics either by virtue of a stronger analgesic activity, better toleration, or both. In addition, many of the compounds of the present invention have been shown to be free of properties which cause addiction based on recognized animal experiments, or exhibit such properties only to a slight extent. Some of the compounds of the present invention also have shown usefulness in the treatment of manic-depressive illness in humans.

The benzomorphanes of the present invention are represented by the formula:

wherein R is methyl, cyclopropylmethyl or cyclobutylmethyl;

R and R" are the same or difierent, and are a straight or branched chain saturated hydrocarbon of 1 to carbon atoms, especially alkyl of 1 to 5 carbon atoms;

X is

R' is a straight or branched chain, saturated or unsaturated hydrocarbon of 1 to 11 carbon atoms, especially straight or branched chain alkyl of 1 to 11 carbon atoms or straight or branched chain alkenyl of 2 to 11 carbon atoms;

R and R are the same or different, and are hydrogen, or a straight or branched chain saturated hydrocarbon of 1 to 4 carbon atoms, especially alkyl of 1 to 4 carbon atoms, or R and R together with the nitrogen atom form a 5- or 6-membered heterocyclic ring wherein the nitrogen atom is the only heteroatom or wherein oxygen is present as a second heteroatom, such as pyrrolidine, piperidine or morpholine; and

A is a bivalent, straight or branched chain, saturated or unsaturated hydrocarbon of 1 to 10 carbon atoms, a bivalent straight or branched chain, saturated or unsaturated hydrocarbon of l to 10 carbon atoms substituted by a member selected from the group consisting of 1 phenyl group, more than 1 phenyl group, and 1 or more phenyls substituted by alkyl, alkoxy, halogen, nitro or acylamino. In particular, it is preferred that A is alkyl of 1 to 10 carbon atoms, alkylene of 1 to 10 carbon atoms, alkenyl of 2 to 10 carbon atoms, or said alkyl, said alkylene, or said alkenyl substituted by phenyl.

These benzomorphanes are produced by reacting a 'benzomorphan of the formula:

HO R" wherein R and R" are as above defined, and Y is hydrogen, methyl, cyclopropylmethyl, cyclobutylmethyl, or a moiety of the formula:

wherein R is cyclopropyl or cyclo'butyl,

in the presence of an acid-binding agent, such as potas- A is as above defined, and Z is CO-X or CN wherein X is as above defined,

to give a compound of the Formula IV:

wherein R, R, R", A and Z are as above defined,

and in the case where Z is CN, converting this group according to methods per se known into the group COX and furthermore if Y is hydrogen or the moiety converting Y into methyl, cyclopropylmethyl or cyclobutylmethyl by a subsequent reaction according to methods which are per se known to obtain compounds of the Formula I. The compounds of the Formula I may be converted into pharmaceutically acceptable non-toxic salts by reaction with suitable acids.

The benzomorphanes of the Formula II can be obtained according to the process of British Pat. No. 1,078,286, according to US. Pat. No. 3,138,603, or according to J. Med. Chem., 7, 123 (1964).

The reaction above described may be carried out in an aqueous medium or in organic solvents, such as benzene, tetrahydrofurane, acetone, dimethylformamide, and the like, at room temperatures or at elevated temperatures. Generally, the boiling point of the particular solvent selected is chosen.

In the case where Z is COX, the compounds of Formula IV are identical to the compounds of Formula I. If Z is CN, then the Compounds IV must be converted as above indicated to the compounds of Formula I.

Among the methods for conversion which can be employed include the conversion into esters (X=OR') and carboxylic acids (X=OH) via imino-ethers, or acid or alkaline hydrolysis, which leads to the primary acid by direct esterification of one of the corresponding acid halides to the esters (X=OR'), or by reaction of the acid halides with ammonia, primary or secondary aliphatic amines to the acid amides The carboxylic acid esters (X=OR') can be converted by hydrolysis into the carboxylic acids (X=OH) or by reaction with ammonia, primary or secondary aliphatic amines to the acid amides and the acid amides can be converted into carboxylic acids by hydrolysis.

The possible conversions indicated above will be explained by the following scheme of formulae:

The benzomorphanes of the present invention can be administered either per se or in the form of their salts, or either the compounds per se or their salts may be formulated into pharmaceutical compositions by techniques per se known by combining the benzomorphan, or the salt thereof, with a pharmaceutically acceptable non-toxic inert diluent or carrier. Among the preferred salts include the sodium and potassium salts in the case of the carboxylic acids, as well as the hydrochlorides, sulphates, phosphates and the like. The liberation of the aminoacids, aminoacidesters and aminoacid-amides on which the salts are based, as well as the conversion of these compounds into their salts, is a reaction which proceeds according to known procedure. Other pharmaceutically acceptable non-toxic salts include the alkali salts, the tartrates, citrates, fumarates, maleates, naphthalenedisulphonates, and the like which are known to be useful for human therapy.

Suitable forms for administering the compounds of the present invention and the pharmaceutical compositions thereof are oral, for example tables, drages, capsules and the like, or by injection by the formation of an injectable solution according to methods which are per se known.

While the amount of the benzomorphanes of the present invention will vary depending upon the severity of the pain, the history of the patient, and the strength of the particular benzomorphan, i.e., its level of analgesic activity, the benzomorphanes of the present invention will generally be administered in individual dosages of about 1 to 100 mg., parenterally or enterally. Such dosages may be administered up to four times per day.

RESULTS OF PHARMACOLOGICAL INVESTIGATIONS In Table 1 set forth below, compounds according to the present invention were compared to known analgesics which cause addiction such as morphine, codeine and pethidine. In Table 2, the structural formulae of representative compounds according to the present invention are designated by number.

Turning to Table 1, this table presents a comparison of the analgesic activity and the compatibility of compounds according to the present invention as compared to known addiction causing analgesics, such as morphine, codeine and pethidine. The toxicity (LD was determined in rats on subcutaneous administration and the analgesic efiect was determined in the heat ray test on the tail of a rat. The therapeutic index (LD :ED was calculated from the two values obtained in these investigations.

A test was further carried out as to whether the products of the process can replace morphine in morphinedependent monkeys or whether morphine-antagonistic effects are present.

As can be seen from Table 1, Compounds 1 and 2 have at least as high a therapeutic index as pethidine. Compound 1 only replaces morphine in morphine-dependent monkeys in considerably higher doses than morphine, codeine and pethidine, while Compound 2 does not replace morphine at all in these animals in tolerated doses.

Compound 3 also does not replace morphine in morphine-dependent monkeys and furthermore exhibits a higher level of analgesic activity and has a higher therapeutic index than any of the comparison compounds.

Compounds 4, 5, 6, 7, 8, 9 and 10 also only cancel the withdrawal symptoms of morphine-dependent monkeys at higher doses than the comparison products. Compounds 8 and 10 exhibit about the same level of analgesic activity as morphine. Both substances have a higher therapeutic index than morphine, because of their lower toxicity. Higher therapeutic indices than morphine are also shown by 7 and 9.

Compounds 11, 12, 13, 14, 15 and 16 only cancel the withdrawal symptoms of morphine-dependent monkeys in higher doses than the comparison substances, or do not do so at all in tolerated doses. Compounds 12 and 14 also exhibit a stronger analgesic activity than morphine.

Compound 17 also exerts a strong analgesic effect and causes withdrawal symptoms in morphine-dependent monkeys, that is to say the substance is a distinctly active to strongly active morphine-antagonistic agent.

In the case of substances which do not cancel the efl'ect of morphine, previous experience has shown that, a priori, the development of a morphine-like addiction or dependence in man is not to be expected.

Compound 18, because of its low toxicity, has a significantly higher therapeutic index than morphine and the other narcotic analgesics employed for comparison.

Compounds 19, 20, 21, 22, 23 and 24, similarly 17, are distinctly stronger active morphine-antagonistic agents. What has been stated for 17, therefore, applies to them. Of these compounds, 19, 20, 21, 22 and 24 furthermore have a significantly stronger analgesic efiect than morphine. Because of their low toxicity, Compounds 18 to 24 have a considerably higher therapeutic index than the comparison products.

Compounds 25, 26 and 27 are not morphine-antago- 8 SUMMARY nistic agents, but cancel the withdrawal symptoms of morphine-dependent monkeys only at higher doses than the comparison products.

Compound 27 exhibits approximately the same level of analgesic activity as morphine, but has a higher therapeutic index than the latter. Compound 26 also has a higher therapeutic index than morphine and the other analgesics employed for comparison.

TABLE 1 Thera- Analgesic efiectpeutio heat ray test on index, Morphine substitution effect on mor- Morphine-antagonistic effect on mor- Toxicity, rat the tail of a rat, LD l phine-dependent monkeys (cancellation phine-dependent. monkeys (provocation Substance LD 50, mg./kg. s.c. EDso, mg./kg. so. EDau of withdrawal symptoms) mgJkg. so. of withdrawal symptoms) mg./kg. so.

Morphine 105 (65-185) 1 52 (0. 66-2. 23) 69 From 2=+ Codeine 229 (139-874) 4 (3. 6-5. 51 From 3:+; from 1 Pethidine 112 (84-136) 5 7 (3. 77. 3) 20 From 1=+; from 1.6=+ 1 From 10=+; from 16=+ -12 21 Up to 12=insignificant -0. 6 370 Up to 18 =insignificant -4 63 Up to 6=insignifiean 5 From 6=+ -10 25 Up to 3=insignifi 2. 2 (1. 72. 9) 114 Up to (i=insignificant; from 12=+ 1. 1 (0. 7-2. 9) 255 Up to 1=in from 10: -3 83 p to 6=ins1gn1ficant from 18 1.7 (1. 3) 94 Fr0m6=+ 6.4 (3. 2-11 0) 39 p to l0=insi ni -0. 8 312 Upgto i=insignificant; 3. 5 (2. 1-5. 6) 72 From 6= -0.8 312 From 6=+; from 12=+ l 5.7 (0. 38. 4) 39 Up to 8=insignificant -8 31 Up to 6=insignificant 2. 9 (0. -8. 3) Up to 0.3=insignificant; from 1=+;

from 4=++. 5 360 0. 43 (0. 19-0. 88) 1, 160 From 0.3=+; from 3=++.

-0.6 417 From 1=+. 0.31 (0.16-0. 55) 3,125 From 1=+. 0. 58 (0. 22-1. 29) -13, 880 Up to 0.1=insignificant; from 0.3=+;

from 5=++. 2. 44 (0. 7-10. 4) 328 Up to 0.3=insignificant; from 1=+. 0.54 (0.2 l. 3) 463 Up to 0.1=insignifica.nt; from 0.3=+;

from 3=++. 5 50 From 6=+ -2. 5 From 6=+ -1.6 156 o N 0'rE.+ slight cancellation or provocation; +=distinct or complete cancellation or provocation.

N-Cm OH: I CzHs TABLE 2Contlnued N-om-q nooo-orn-o (a N-om 0,11,0-0 o-wnm-o H,

N-cmnooo-mm-o H;

N-CHz- EXAMPLE 1 taken up in 60 ccs. of dimethylformamide, 4.3 g. of 'ybromobutyric acid ethyl ester are added dropwise and the mixture stirred for 18 hours at 60. The reaction mixture is concentrated in vacuo and distributed between water and ether. After separating off the ether phase, the water phase is extracted twice more with methylene chloride, the combined organic phases are dried by means of zene, again evaporated to dryness in vacuo, the residue is 75 sodium sulphate, the solvent is stripped ofi in ivacuo and the residue is distilled in vacuo, whereupon 4.9 g. of 2,5,9- trimethyl 2' [3 ethoxycarbonylpropoxy-(1)]-6,7-benzomorphan of boiling point 192-202 are obtained as a viscous oil.

The same compound is obtained if 4.6 g. of 2,5,9-trimethyl-2-hydroxy-6,7-benzomorphan and 3.3 g. of sieved potassium hydroxide in 100 ccs. of absolute acetone are heated for 12 hours under reflux, 4.3 g. of brornobutyric acid ethyl ester are added dropwise, the mixture is stirred for a further 12 hours at the boil and filtered, the filtrate concentrated in vacuo and the residue distilled in vacuo.

EXAMPLE 2 4.9 g. of ethyl 2,9-dimethyl-2'-hydroxy-6,7-benz0- morphan are dissolved in 100 ccs. of dimethylformamide, mixed with 1.12 g. of powdered potassium hydroxide, and the mixture stirred for 30 minutes at room temperature. A solution of 1.87 g. of chloroacetamide in 20 ccs. of dimethylformamide is then added dropwise over the course of 20 minutes and the whole stirred for 12 hours at 70. The precipitate is filtered off and the filtrate is concentrated in vacuo, whereupon crystallization occurs. The crystalline product is filtered off and recrystallized from acetone. The 5-ethyl-2,9-dimethyl-Z-carbamoyl-methoxy- 6,7-benzomorphan thus obtained contains half a mol of acetone of crystallization and melts at 100 to 102. The acetone can be removed by drying at 50 in vacuo.

EXAMPLE 3 4.6 g. of 2,5,9 trirnethyl-2'-hydroxy-6,7-benzomorphan are converted into the sodium salt in the manner described under Example 1. 100 ccs. of dimethylfor rnamide and 2.6 g. of sodium chloroacetate are added and the mixture is warmed slowly to 60 whilst stirring. It is stirred for 12 hours at this temperature, the solvent is removed in vacuo, the residue is taken up in as little water as possible and the solution adjusted to pH 8 by adding hydrochloric acid. The precipitate which forms is filtered off, washed with water and acetone and dried in vacuo. The 2,5,9-trimethyl 2' carboxymethoxy-6,7-benzomorphan decomposes from 205 onwards.

EXAMPLE 4 9.8 g. of 5-ethyl-2,9-dimethyl-2'-hydroxy-6,7-benzomorphan are suspended in 200 ccs. of absolute methanol, mixed with a solution of 0.92 g. of sodium in 20 ccs. of absolute methanol, and stirred for one hour at the boil. The methanol is distilled off in vacuo, 50 cc. of absolute benzene are added, the whole is stirred for 4 hour at room temperature and the solvent is removed in vacuo. The solid residue is dissolved in 120 ccs. of dimethylformamide. After adding 4.6 g. of -chlorobutyronitrile, the reaction mixture is warmed for 18 hours to 60, whilst stirring, and is concentrated in vacuo, and the residue is distributed between water and ether. The undissolved constituents are filtered off. The ether phase is separated off and dried with sodium sulphate. After removal of the ether, the residue is distilled in vacuo and 5-ethyl-2,9-diis obtained as an oil of boiling point 198-204", which crystallizes easily.

5 ethyl-2,9-dimethyl-2'-cyanomethoxy-6,7-benzom0rphan of boiling point 190-193 is obtained by analogous procedure from 5-ethyl-2,9-dimethyl-2'-hydroxy-6,7- benzomorphan and chloracetonitrile.

EXAMPLE 5 3.9 g. of 2-cyclobutylmethyl-5,9-dimethyl-2-[3-ethoxycarbonylpropoxy-(l)]-6,7-benzornorphan are dissolved in a mixture of 20 ccs. of absolute ether and ccs. of absolute methanol, mixed with 4.9 ccs. of 2-normal methanolic sodium methylate solution, shaken, and stirred for 12 hours at room temperature after addition of 0.2 cc. of water. The solution is evaporated to dryness in vacuo 14 in a rotary evaporator. The residue consists of the sodium salt of 2-cyclobutylmethyl-5,9-dimethyl-2-[3-carboxypropoxy-(l)]-6,7-benzomorphan. Colorless powder; decomposition from 225 onwards.

The same compound is obtained if 4.0 g. of 2-cycl0- butylmethyl-S,9-dimethyl-2'-[3 ethoxycarbonylpropoxy- (1)]-6,7-benzomorphan in 50 ccs. of a mixture of 50 ccs. of dioxane and 10 cos. of water containing 0.4 g. of sodium hydroxide are heated for 4 hours under reflux and subsequently evaporated to dryness.

EXAMPLE 6 5.7 g. of 5-ethyl-2,9-dimethyl-2-cyanomethoxy-6,7- benzomorphan are dissolved in 30 ccs. of concentrated sulphuric acid and left to stand for 15 hours at room temperature. The mixture is poured onto ice, rendered alkaline with sodium hydroxide solution whilst cooling and extracted with benzene-butanol (1:1), the extract is dried by means of sodium sulphate, the solvent is removed in vacuo and the residue is recrystallized from acetone. The resulting product is identical with the 5- ethyl-2,9 dimethyl-2-carbamoylmethoxy-6,7-benzomorphan described in Example 2.

EXAMPLE 7 5.7 g. of 5-ethyl-2,9-dimethyl-2-cyanomethoxy-6,7- benzomorphan in 50 ccs. of concentrated hydrochloric acid are stirred for 12 hours under reflux. The mixture is subsequently evaporated to dryness, the residue is taken up in water, and a solution of 2.4 g. of sodium hydroxide in water is added. After evaporation, a solid residue is obtained, which is treated with absolute ethanol. The sodium chloride is removed by filtration, the filtrate is again evaporated to dryness, the residue is triturated with absolute ethanol, and the product is filtered off and dried in vacuo. The sodium salt of 5-ethyl-2,9-dimethyl-2- carboxymethoxy-6,7-benzomorphan, which is thus obtained, decomposes from 193 onwards.

The same compound is obtained if 5-ethyl-2,9-dimethyl- 2'-carbamoylmethoxy-6,7-benzomorphan is employed in place of S-ethyl-2,9-dimethyl-2'-cyanornethoxy-6,7-benzomorphan in the reaction described above.

EXAMPLE -8 A solution of 3.8 g. of 2-cyclopropylmethyl-5,9-dimethyl-2- [ethoxycarbonylpr0poxy-( 1) ]-6,7-benzomorphan in 100 cos. of ethanol is saturated with ammonia and heated for several hours to -100 in an autoclave. After evapporation, 2-cyclopropylmethyl 5,9 dimethyl-2-[3-carbamoylpropoxy (1)] 6,7 benzomorphan is obtained. Melting point of the hydrochloride, 176-179".

EXAMPLE 9 5.0 g. of 2,5,9-trimethyl-2-carboxymethoxy-6,7-benzomorphan are dissolved in ccs. of absolute ethanol and stirred for 3 hours under reflux, while passing in hydrogen chloride. Thereafter the mixture is evaporated to dryness, the residue is taken up in 100 ccs. of absolute ethanol and the mixture is again heated to the boil for 3 hours while passing in hydrogen chloride. After removal of the solvent in vacuo, the residue is dissolved in a little water, and the solution is rendered alkaline with dilute sodium hydroxide solution whilst cooling and is extracted three times with methylene chloride-ether. The combined extracts are dried by means of sodium sulphate, concentrated and acidified with a solution of tartaric acid in ether, whereupon the tartrate of 2,5,9-trimethyl-2'-ethoxycarbonylmethoxy-6,7- benzomorphan precipitates. Melting point EXAMPLE 10 1.5 g. of hydrogen chloride are passed into a solution of 5.7 g. of 5-ethyl-2,9-dimethyl-2'-cyanomethoxy-6,7-benzomorphan in 30 ccs. of absolute ethanol, while cooling. The reaction mixture is left to stand for two hours at room temperature and is evaporated to dryness in vacuo. The

'residue is taken up in water, and the solution is stirred for 10 minutes, covered with a layer of ether and rendered alkaline with dilute sodium hydroxide solution while cooling. After separating 011 the ether phase, the aqueous 5 phase is extracted twice more with ether. The combined ether solutions are dried with sodium sulphate, concentrated, and the residue distilled in vacuo. 5-ethyl-2,9-dimethyl 2 ethoxycarbonylmethoxy 6,7-benzomorphan boils at 176180/0.1 mm. Hg.

EXAMPLE 1 1 'until the evolution of gas has ended and is evaporated to dryness in vacuo. The residue is taken up in 100 ccs. of dry ethylene chloride and 3.0 g. of dimethylamine are passed in whilst cooling. After 15 minutes stirring at room temperature, 50 ccs. of 4-normal sodium hydroxide solution are added, and the ethylene chloride phase is separated off, dried by means of sodium sulphate and evaporated to dryness in vacuo. The residue is taken up in acetone and rendered acid with a solution of hydrochloric acid in ether. On further addition of ether, the hydrochloride of 5-ethyl- 2,9 dimethyl 2' N,N-dimethylcarbamoylmethoxy-6,7- benzomorphan precipitates. Melting point 206208.

The same compound is obtained if 5-ethyl-2,9-dimethyl- 2'-hydroxy-6,7-benzomorphan is reacted with chloracetic acid dimethylamide in the manner described under Example 2.

The following compounds are produced in a manner analogous to the preceding examples:

2,5,9-trimethyl-2-(u-ethoxycarbonyl-p-methylbenzyl0xy)- 6,7-benzomorphan, boiling point 210 to 212 C.

2,5 ,9-trimethyl-2- a-ethoxycarbonyl-p-chlorobenzyloxy 6,7-benzomorphan, boiling point 215 to 218 C.

2,5,9trimethyl-2-(a-ethoxycarbonyl-p-nitrobenzyloxy)- 6,7-bcnzomorphan, decomposition of the hydrochloride from 167 C. onwards.

2,5,9-trimethyl-2- (u-ethoxycarhonyl-p-methoxyhenzyloxy)-6,7-benzomrphan, decomposition of the hydrochloride from 134 C. onwards.

2,5-9-trimethyl-2'-(u-ethoxycarbonyl-p-acetamidobenzyloxy)-6,7-benzomorphan, decomposition of the hydrochloride from 158 C. onwards.

2,5,9-trimethyl-2'- [3-carboxypropoxy-( 1 ]-6,7-henzomorphan, melting point of the sodium salt 144 C.

2,5,9-trimethyl-2'-(a-carboxy-p-methoxybenzyloxy)-6,7-

benzomorphan, decomposition of the sodium salt from 176 C. onwards.

2,5,9-trimethy1-2'-(a-carboxy-p-chlorobenzyloxy)-6,7-

benzomorphan, decomposition of the sodium salt from 205 C. onwards. -ethyl-2,9-dimethyl-2'- [3-ethoxycarbony1propoxy-( 1 6,7-benzomorphan, boiling point 202 to 206 C. 5-ethy1-2,9-dimethyl-2'- 1-ethoxycarbonylpropoxy-( 1 6,7-benzomorphan, boiling point 206 to 212 C. 5-ethyl-2,9-dimethy1-2- [Z-ethoxyc arbonylpropoxy- 2) 6,7-benzornorphan, boiling point M 180 to 182 C. 5-ethyl-2,9-dimethyl- 2'- 3-methoxycarbonylprop-2-en- 1- yloxy)-'6,7-benzomorphan, boiling point 194 to 202 C. 5-ethyl-2,9-dimethyl-2'-[ 10-ethoxycarbonyldecyloxy-(1 6,7-benzomorphan, purified by Craig distribution; oil; calculatedzN, 3.06; found: N, 3.00. 5-ethyl-2,9-dimethyl-2'- (u-ethoxycarbonylbenzyloxy) -6,7- benzomorphan, decomposition of the hydrochloride from 80 C. onwards. 5-ethyl-2,9-dimethyl-2'- [3-carboxypropoxy-( 1 ]-6,7-

benzomorphan, decomposition of the sodium salt from 208 C. onwards.

5-ethyl-2,9-dimethyl-2- 1-carboxypropoxy-( 1) ]-6,7-

benzomorphan, decomposition of the sodium salt from C. onwards.

5 -ethyl-2,9-dimethy1-2- 2-carboxypropoxy-( 2) ]-6,7-

benzomorphan, decomposition of the monohydrate of the sodium salt from 248 C. onwards.

5 -ethyl-2,9-dimethyl-2- a-carboxybenzoyloxy) -6,7-

benzomorphan, decomposition of the dihydrate of the sodium salt from 216 C. onwards.

5-ethyl-2,9-dimethyl-2'- (3-carboxyprop-2-en-1 -yloxy) 6,7-benzom0rphan, decomposition of the monohydrate of the sodium salt from 225 C. onwards.

5-ethyl-2,9-dirnethyl-2-[1-piperidinocarbonylethoxy-( 1 6,7-benzomorphan, hydrochloride H O, decomposition from 80 C. onwards. 2-cyclopropylmethyl-S,9 dimethyl-2'-isopropoxycarbonylmcthoxy-6,7-benzomorphan, boiling point 188 to 192 C.

2-cyclopropylmethyl-5,9-dimethyl-2'- (undec- 10-en-1 -yloxycarbonylmethoxy)-6,7-benzom0rphan, melting point of the hydrochloride 138 to 142 C.

2-cyc1opropylmethyl-5,9-dimethyl-2'- 3-ethoxycarh onylpropoxy-( 1 ]-6,7-benzomorphan, boiling point 204 to 212 C.

2-cyclopropylrnethyl-5,9-dimethyl- '-ethoxycarbonylmethoxy-6,7-benzornorphan, boiling point 194 to 198 C.

2-cyclopropymethyl-5,9-dimethyl-2-[ l-ethoxycarbonylethoxy-( 1 ]-6,7-benzomorphan, boiling point to 178 C.

2-cyclopropylmethyl-5, 9-dimethyl-2'- a-ethoxycarbonylp-nitrobenzyloxy)-6,7-benzomorphan, melting point of the hydrochloride 127 to 129 C.

(decomposition) 2-cyclopropylrnethyl-5,9-dimethyl-2- a-ethoxycarbonylp-chlorobenzyloxy)-6,7-benzomorphan, boiling point 223 to 226 C.

2-cyclopropylrnethyl-5,9-dimethyl-2'- a-ethoxycarbonylp-methylbenzyloxy)-6,7benzomorphan, boiling point 213 to 218 C.

Z-cyclopropylmethyl-S,9-dimethy1-2'-(a-ethoxycarbonylp-methoxybenzoyloxy)-6,7-benzomorphane, boiling point 220 to 223 C.

2-cyclopropy1methyl-5,9-dimethyl-Z'-carboxymethoxy-6,7- benzomorphan, decomposition of the hemihydrate of the sodium salt from 192 C. onwards.

2-cyclopropylmethyl-5,9-dimethy1-2'- l-carb oxyethoxy- (1)]-6,7-benzornorphan, decomposition of the monohydrate of the sodium salt from 183 C. onwards.

2- cyclopropylmethyl-5,9 dimethyl-2'- 3-carboxypropoxy- (1)]-6,7-benzomorphan, decomposition of the sodium salt from 110 C. onwards.

2-cyclopropy1methyl-5,9-dimethyl-2'- [3 -N,N-dimethylcarbamoylpropoxy- 1) ]-6,7-benzomorphan, boiling P01111033 to 232 C.

2-cyclopropylmethyl-5-etl1y1-9-methyl-2'- 3-ethoxycarbonylpropoxy-(l ]6,7-benzomorphan, boiling point 202 to 210 C.

2-cyc1opropyln1ethyl-S-ethyl-9-rnethyl-2'-ethoxycarbonyl methoxy-6,7-benzomorphan, melting point of the hydrochloride 180 to 182 C.

2 cyclopropylrnethyl 5-ethyl-9-methyl-2'-a-ethoxycarbonyl-benzyloxy 6,7-benzornorphan, boiling point 225 to 228 C.

2 cyclopropylmethyl 5-ethyl-9-methyl-2'-[2-ethoxycarbonyl-propoxy (2)] 6,7 benzornorphan, boiling point 174 to 184 C.

2 cyclopropylmethyl 5-ethyl-9-methy1-2'-[IO-ethoxycarbonyl-decyloxy (1) ]-6,7-benzomorphan, melting point of the hydrochloride 118 to 121 C.

2 cyclopropylmethyl-S-ethyl-9-methyl-2-(3-methoxycarbonyl-prop 2-en-l-yloxy)-6,7-benzomorphan, boiling point 203 to 210 C.

2 cyclopropylmethyl -ethyl-9-methyl-2-carboxymethoxy 6,7-benzomorphan, decomposition of the sodium salt from 110 C. onwards.

2 cyclopropylmethyl 5-ethyl-9-methyl-2'-[2-carboxypropoxy-(Z)]6,7-benzomorphan, decomposition of the sodium salt from 75 C. onwards.

2 cyclobutylmethyl 5,9-dimethyl-2'-[3-ethoxycarbonylpropoxy (1)]-6,7-benzomorphan, boiling point 232 to 236 C.

2 cyclobutylmethyl 5,9 dimethyl-2'-ethoxycarbonylmethoxy 6,7-benzomorphan, boiling point 210 to 214 C.

2 cyclobutylmethyl-S,9-dimethyl-2-carboxymethoXy-6,7-

benzomorphan, decomposition of the monohydrate of the sodium salt from 180 C. onwards.

What is claimed is:

1. An analgesic composition which comprises an analgesically effective amount of a benzomorphan of the formula wherein R is methyl, cyclopropylmethyl or cyclobutylmethyl;

R and R" are the same or different, and are methyl or ethyl;

A is straight or branched chain alkylene or alkylidene of 1 to 4 carbon atoms or alkenylene of 2 to 4 carbon atoms, unsubstituted or substituted by phenyl or phenyl substituted by methyl, methoxy, chloro, nitro, or acetylamino;

X is

RI on, OR" or N wherein R' is a straight or branched chain alkyl of 1 to 11 carbon atoms or straight or branched chain alkenyl of 2 to 11 carbon atoms, and R and R are the same or different, and are hydrogen, alkyl of 1 to 4 carbon atoms, or R and R together with the nitrogen atoms form a pyrrolidine, piperidine, or morpholine ring; in combination with a pharmaceutically acceptable, nontoxic, inert diluent or carrier.

2. An analgesic composition according to claim 1 wherein R' is straight or branched chain alkyl of 1 to 3 carbon atoms or straight or branched chain alkenyl of 2 or 3 carbon atoms, R and R are the same or different, and are hydrogen or alkyl of 1 or 2 carbon atoms, or R and R together with the nitrogen atom form a piperidine ring.

3. An analgesic composition according to claim 1 wherein R' is straight or branched chain alkyl of 1 to 3 carbon atoms or straight or branched chain alkenyl of 2 or 3 carbon atoms and R and R are methyl.

4. An analgesic composition according to claim 1 wherein the benzomorphan is 5-ethyl-2,9-dimethyl-2'-[3- ethoxycarbonylpropoxy- 1 -6,7-benzomorphan.

5. An analgesic composition according to claim 1 wherein the benzomorphan is 2-cyclopropylmethyl-5,9- dimethyl-2' [3 ethoxycarbonylpropoxy-(l)]6,7-benzomorphan.

6. An analgesic composition according to claim 1 wherein the benzomorphan is 2-cyclopr0pylmethyl-5- ethyl-9-methyl-2'-[3 ethoxycarbonylpropoxy (1)]-6,7- benzomorphan.

7. An analgesic composition according to claim 1 wherein the benzomorphan is 2-cyclopropylmethyl-5,9- dimethyl-2'-carboxymethoxy-6,7-benzomorphan.

8. An analgesic composition according to claim 1 wherein the benzomorphan is 2-cyclopropylmethyl-5,9- dimethyl-2-[3-ethoxycarbonylpropoxy l) ]-'6,7-benzomorphan.

9. An analgesic composition according to claim 1 wherein the benzomorphan is 2-cyclopropylmethyl-5,9- dimethyl-2'- [3-carboxypropoxy-( l ]6,7-benzomorphan.

10. An analgesic composition according to claim 1 in oral administration form.

11. An analgesic composition according to claim 1 in the form of an injectible solution.

12. A method of effecting analgesia in humans and animals which comprises administering to a human or an animal in need thereof an analgesically effective amount of a benzomorphan of the formula wherein R is methyl, cyclopropylmethyl or cyclobutylmethyl;

R' and R" are the same or difierent, and are methyl or ethyl;

A is straight or branched chain alkylene or alkylidene of 1 t0 4 carbon atoms or alkenylcne of 2 to 4 carbon atoms, unsubstituted or substituted by phenyl or phenyl substituted by methyl, methoxy, chloro, nitro or acetylamino;

X is

wherein R' is a straight or branched chain alkyl of 1 to 11 carbon atoms or straight or branched chain alkenyl of 2 to 11 carbon atoms, and

R and R are the same or difierent, and are hydrogen, alkyl of 1 to 4 carbon atoms or R and R together with the nitrogen atom form a pyrrolidine, piperidine or morpholine ring.

13. A method according to claim 12 wherein R' is straight or branched chain alkyl of 1 to 3 carbon atoms or straight or branched chain alkenyl of 2 or 3 carbon atoms, R and R are the same or diiferent, and are hydrogen or alkyl of 1 or 2 carbon atoms, or R and R together with the nitrogen atom form a piperidine ring.

14. A method according to claim 12 wherein R" is straight or branched chain alkyl of 1 to 3 carbon atoms or straight or branched chain alkenyl of 2 or 3 carbon atoms and R and R are methyl.

15. A method according to claim 12 wherein the benzomorphan is S-ethyl 2,9 dimethyl-2'-[3-eth0xycarbonylpropoxy- 1) ]-6,7-benzomorphan.

16. A method according to claim 12 wherein the benzomorphan is 2 cyclopropylmethyl 5,9 dimethyl 2' [3- ethoxycarbonylpropoxy-( 1) ]6,7-benzomorphan.

17. A method according to claim 12 wherein the benzomorphan is 2-cyclopropylmethyl-5-ethyl 9-methyl-2'-[3- ethoxycarbonylpropoxy-( 1) ]6,7-benzomorphan.

18. A method according to claim 12 wherein the hememorphan is 2-cyclopropylrnethy1-5,9-dimethyl-2'-carboxymethoxy-6,7-benzomorphan.

19. A method according to claim 12 wherein the hememorphan is 2 cyclobutylmethyl 5,9 dimethyl 2-[3 ethoxycarbonylpropoxy-( l ]-6,7-benzomorphan.

20. A method according to claim 12 wherein the henzomorphan is 2 cyclobutylmethyl 5,9 dimethy1-2-[3- carboxypropoxy-( 1 ]-6,7-benzomorphan.

21. A method according to claim 12 wherein the administration is oral.

22. A method according to claim 12 wherein the administration is by injection.

20 References Cited UNITED STATES PATENTS 5/1967 Kutchan et al. 260294.7 10/1967 Gordon et a1. 260294 OTHER REFERENCES 10 JEROME D. GOLDBERG, Primary Examiner U.S. C1. X.R. 424-248, 274 

